Elevator systems are in widespread use. The machine for controlling movement of an elevator car may be hydraulic or traction-based. Elevator machines include machine brakes that effectively hold the elevator car stationary at a landing to allow passengers to enter or exit the car.
Elevator systems typically include safeties, which are braking devices that are used under conditions in which the elevator car is moving in an undesired manner. A governor device is typically roped to a safety on one side of the elevator car. If the elevator car moves at an undesirably high speed, for example, the governor activates the safety causing it to engage a guiderail to stop the elevator car. Some safety configurations include a linkage between safeties on opposite sides of the elevator car. When the governor activates one of the safeties the linkage operates to activate the other and the safeties engage a guiderail on both sides of the elevator car.
One issue presented during safety activation on a descending elevator car is that the inertia of the upwardly moving counterweight tends to cause the counterweight to continue moving even though the elevator car has stopped. Eventually the counterweight stops and may bounce because of slack in the roping that results from the continued movement of the counterweight after safety activation to stop the elevator car.
High rise elevators may include a tie down compensation mechanism near the bottom of the hoistway that tends to arrest counterweight jump. Tie down compensation mechanisms add cost and require additional space in an elevator system. It would be beneficial to be able to address the possibility of counterweight or elevator car jump without requiring a typical tie down mechanism.